Field of the Invention
The invention relates to a bipolar cascadable circuit configuration for signal limitation and field intensity detection, having a limiter stage which generates an output signal that is supplied to a detection stage, and a power supply feeding current to the detection stage, wherein the power supply and therefore an output signal of the detection stage are dependent on a supply voltage.
One such circuit configuration is described, for instance, in the paper by J. Fenk, B. Birth, R. G. Irvine, P. Sehrig and K. R. Schon, entitled "An RF-Front End For Digital Mobile Radio", in IEEE 1990, Bipolar Circuits and Technology Meeting 11.2. Such circuits are cascadable, in that case with seven stages, producing a reception circuit of the kind often needed not only in radio and television technology but also in the mobile radio field. To that end, the limiter amplifier stages are connected in series with one another, while the field intensity detector stages, each assigned to the various limiter amplifier stages, are connected in parallel on the output side.
In wireless equipment, a long battery life is generally sought. Moreover, the batteries should be low in weight and small in size, to assure a compact construction of the equipment. In order to achieve that, on one hand it requires reducing the power consumption, and/or on the other hand minimizing the number of individual battery cells, which demands a lower minimum supply voltage of the receiving circuit. The resultant disadvantage is that the circuit configuration is dependent on fluctuations of the supply voltage.